My guess is that someone has clicked your name found on another user's page. It might be clicking your name through the comments you made or through the hubtivity of the user. It might also be that the user has suggested links to your hubs on his/her own page. I would occasionally find my sister's (cheerfulnuts) subdomain as one of my traffic sources. She has included a link to my account on her profile information, that explains why her subdomain was listed among my sources.